The present invention relates to a system and a method for controlling contents to thereby implement control of reproduction and storage of the contents, and is concerned with contents management techniques for controlling reproduction and storage of contents on the part of users, in particular, against the contents in distribution.
Up to now, digital contents (hereinafter referred to merely as contents), such as still picture data, video data, audio data, and so forth, have been made available to users through the intermediary of communications media such as Internet, digital broadcast, and so forth, or a medium such as a CD-ROM, DVD-ROM, and so forth. The contents described are characterized in that they can be copied with ease. It is therefore suspected that the contents can be improperly acquired by a third party.
For this reason, in Reference 1 described hereunder, the following techniques are disclosed as means for transmitting a control signal for contents, intended for copy control of DVD contents. More specifically, the techniques include:
(1) addition of a copy control signal to contents, according to the analog specification CGMS-A, and so forth, of CGMS (Copy Generation Management System)
(2) embedding of the copy control signal, in the contents, by a digital watermark
Further, in Reference 2 described hereunder, there are disclosed the digital watermark management system wherein a plurality of pieces of information are embedded in contents by use of a plurality of digital watermarks for which endurances differ from each other, and when detecting the digital watermarks, the deterioration state of the contents is detected from the information embedded as detected, and the digital watermark management method.    Reference 1: “Copy Protection for DVD Video” by Jeffrey A Bloom, Ingemar J. Cox, Ton Kalker, Jean-Paul M. G. Linnartz, Mathew L. Miller, and Brendan S. Traw, Proceedings of the IEEE, Vol. 87, No. 7, pp. 1267-pp. 1276, July 1999    Reference 2: Japanese Published Unexamined Patent Application No. 2002-232693